Windows
WinResizer
A no-framework Win32 GUI tool that forces ANY window to become resizable and moves/resizes it to an exact size — even if the target application was written without a sizing border (WS_THICKFRAME). It adds a real sizing border, reapplies the requested geometry and includes an optional "Enforce" watchdog timer that re-applies everything for stubborn apps that clamp their own size.
Build from source: download
WinResizer.cpp and build.bat, then run build.bat in the folder (requires MinGW-w64 / g++). Free and open — no installation needed.
heYYape